title: Appliance-induced osteopenia of dentoalveolar bone in the rat: effect of reduced bone strains on serum bone markers and the multifunctional hormone leptin.
abstract: To understand, in greater detail, the molecular mechanisms regulating the complex relationship between mechanical strain and alveolar bone metabolism during orthodontic treatment, passive cross-arch palatal springs were bonded to the maxillary molars of 6-wk-old rats, which were killed after 4 and 8 d. Outcome measures included serum assays for markers of bone formation and resorption and for the multifunctional hormone leptin, and histomorphometry of the inter-radicular bone. The concentration of the bone-formation marker alkaline phosphatase (ALP) was significantly reduced at both time points in the appliance group, accompanied by a 50% reduction in inter-radicular bone volume; however, osteocalcin (bone Gla protein) levels remained unaffected. Bone collagen deoxypyridinoline (DPD) crosslinks increased 2.3-fold at 4 d only, indicating a transient increase in bone resorption; in contrast, the level of the osteoclast-specific marker, tartrate-resistant acid phosphatase 5b (TRACP 5b), was unchanged. Leptin levels closely paralleled ALP reductions at both time points, suggesting an important role in the mechanostat negative-feedback loop required to normalize bone mass. These data suggest that an orthodontic appliance, in addition to remodeling the periodontal ligament (PDL)-bone interface, may exert unexpected side-effects on the tooth-supporting alveolar bone, and highlights the importance of recognizing that bone strains can have negative, as well as positive, effects on bone mass.
authors.affiliation: Faculty of Dentistry, National University of Singapore, Singapore; National Dental Centre, Singapore.
authors.forename: Jayaseelan K
authors.initials: JK
authors.lastname: Vinoth
authors.forename: Kaval J
authors.initials: KJ
authors.lastname: Patel
authors.forename: Wei-Song
authors.initials: WS
authors.lastname: Lih
authors.forename: Yian-San
authors.initials: YS
authors.lastname: Seow
authors.forename: Tong
authors.initials: T
authors.lastname: Cao
authors.forename: Murray C
authors.initials: MC
authors.lastname: Meikle
mesh_terms: D000135:Acid Phosphatase / Q000097:blood; D000469:Alkaline Phosphatase / Q000097:blood*; D000539:Alveolar Process / Q000378:metabolism* / Q000473:pathology; D000596:Amino Acids / Q000097:blood; D000818:Animals; D015415:Biomarkers / Q000097:blood; D001851:Bone Diseases, Metabolic / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D001862:Bone Resorption / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D007527:Isoenzymes / Q000097:blood; D020738:Leptin / Q000097:blood*; D008297:Male; D009967:Orthodontic Appliances / Q000009:adverse effects*; D015675:Osteocalcin / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D000596:Amino Acids; D015415:Biomarkers; D007527:Isoenzymes; D020738:Leptin; D015675:Osteocalcin; C036020:deoxypyridinoline; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase
keywords: alkaline phosphatase; deoxypyridinoline crosslinks; leptin; osteopenia; tartrate-resistant acid phosphatase 5b